The use of magnesium and potassium salts for dietary supplementation is well known. One useful composition for such supplementation is potassium magnesium citrate (PMC). Unfortunately, early compositions of PMC exhibited poor processing and poor thermal stability. It is desirable to have a new PMC composition suitable for dietary supplementation that possesses superior processing and thermal stability.
A typical reaction for the production of tetra potassium magnesium dicitrate involves both the magnesium and potassium carbonates according to the reaction:10K2CO3+(MgCO3)4Mg(OH)2.5H2O+10H3(C6H2O7)→5K4Mg(C6H5O7)+21H2O+14CO2
Magnesium Carbonate USP is more correctly identified as magnesium carbonate magnesium hydroxide and its correct stoichiometric formula is shown in the above reaction equation. In practice, the reaction seems to go as predicted. The carbonates and hydroxides react with citric acid producing a material with the empirical formula of K4Mg(C6H5O7)2 plus carbon dioxide and water.
A number of these problems were addressed with the introduction of dual mineral salts of potassium, magnesium, and citrate. In U.S. Pat. No. 4,985,593, Walsdorf et al., described to a new composition of matter comprising magnesium, potassium and citrate in a single compound which allowed for effectively supplementing dietary magnesium and potassium by administering magnesium, potassium and citrate in a single salt. U.S. Pat. No. 4,895,980, also to Walsdorf, disclosed methods of making that aforementioned composition. Finally, U.S. Pat. No. 5,219,889 to Walsdorf et al., disclosed methods of supplementing dietary potassium, magnesium, and citrate by oral administration in which the ratio of potassium:magnesium:citrate is 4:1:2.
While the Walsdorf and other compositions addressed many of the earlier problems in the area of potassium and magnesium dietary supplementation, some problems remained. Improved processing, in addition to decreasing production costs, are expected to result in potentially new formulations and finished product dosage forms, which can improve shelf stability of the finished product. Additionally, improved thermal stability of the dietary supplement is desirable.
Earlier compositions of PMC targeted a ratio of K:Mg:Citrate of 4:1:2 but there was little control over the resulting compound. The result was a salt or mixture having a potassium:magnesium:citrate ratio near to 4:1:2 in which neither the completeness of reaction nor the final stoichiometry of the resulting compound was adequately determined. This resulted in batches of PMC that had differing properties including varied thermal stability, final stoichiometry and processability. The present invention discloses a pure PMC which possesses a precisely defined stoichiometry whereby stoichiometry is precisely controlled by process conditions. The present invention also encompasses a process for making the new composition. The resulting composition is useful as a dietary supplement yet does not suffer from the deficiencies of the earlier compositions.
To this end, a new composition of potassium magnesium citrate has been made which exhibits enhanced thermal stability and is more amenable to analytical quality control monitoring. These advantages are realized while preserving the usefulness as a dietary supplement enjoyed by earlier compositions.